In recent years, an IC card and a mobile electronic device has become popular and much further thinning of a semiconductor component has been desired. Consequently, a conventional semiconductor chip having a thickness of approximately 350 μm has to be further thinner to be in the range of 50 to 100 μm or less.
To form a semiconductor chip, after a front surface circuit formation is carried out, a predetermined thickness of the semiconductor chip is ground from a rear face, and a dicing is carried out for every circuit. As another method, after a surface circuit formation is carried out, a groove having a depth more than a predetermined depth from a circuit surface is formed, and a rear face is ground in such a manner that a semiconductor chip has a predetermined thickness (dicing before grinding method) to form a semiconductor chip.
A semiconductor chip that has been fixed on a pressure sensitive adhesive sheet such as a dicing sheet to prevent chips from being separated is brought to a pickup process. In the case in which a chip on the pressure sensitive adhesive sheet is picked up, the pressure sensitive adhesive sheet under the rear face of the chip is pushed up by means of a fine needle to reduce an area of contact with the pressure sensitive adhesive sheet. The chip that has been pushed up by a fine needle is sucked by means of a suction collet from the upper surface side of the chip, and is detached from the pressure sensitive adhesive sheet. The chip is then transferred to a die pad of a chip substrate or the like.
Since a chip has been thinned, the pushing up of a chip by means of a fine needle delivers a considerable damage to the chip. A semiconductor device in which a chip that has been damaged is used possesses lower reliability, for instance, a package crack occurs by receiving a heat history. In addition, in the case in which the damage suffered is serious, a chip may be broken due to the pushing up of the chip in some cases.
To solve such problems, a pickup method in which the pushing up of a chip by means of a fine needle is not carried out is studied (Japanese Patent Application Laid-Open Publication No. 2003-179126 (see Patent document 1)). In the pickup method, a suction table of a porous material is used in place of a pressure sensitive adhesive tape, and a suction of a suction table is stopped to cancel the holding force of a chip in the case in which a chip is picked up. However, in this method, a gap between chips cannot be sealed and an air leaks. Moreover, a leak amount increases as a chip is picked up. By this, a holding force to a remaining chip that is not picked up is reduced, and a location of a chip is out of alignment by a vibration, whereby a collet cannot catch a chip.    Patent document 1: Japanese Patent Application Laid-Open Publication No. 2003-179126
The present invention was made in consideration of the above problems, and an object of the present invention is to provide a fixing jig which can unmovably suction a chip group produced by segmenting a semiconductor wafer into pieces, and can suction one chip by detaching the chip selectively and reliably from the chip group.
Another object of the present invention is to provide a pickup method wherein the pushing up of a chip is not required and a force for holding a chip that is not picked up is not varied as a pickup is progressed to pick up the chip reliably and a pickup apparatus suitable for achieving the pickup method by using the above fixing jig.